Insulated reel mechanism for highpower aircraft trailing antenna



March 3, 1970 R, L, CARREL ETAL 3,499,171

INSULATED REEL MECHANISM FOR HIGH-POWER AIRCRAFT TRAILING ANTENNA FiledMy 28, 1964 2 Sheets-Sheet 1 Yr ,l :e

In Km w n R m g; J v

Y gs) l 'n o al) t?) IR /X n f 0 N a gf :CD O: .@RQ g M l f@ 'n m K n gQ Q CK g W s Q lNvENToRs Q g: m ROBERT L. cARREL w z RICHARD c. FENwlcKROBERT A. FowLER ATTORNEY March 3, 1970 R, L, CARREL ETAL 3,499,171

INSULATED REEL MECHANISM FOR HIGH-POWER AIRCRAFT TRAILING ANTENNA FiledMay 28, 1964 2 Sheets-Sheet 2 58 INVENTORS 3 ROBERT L. CARREL RICHARD C.FENWICK ROBERT A. FOWLER BYW- ATTORNEY United States Patent O 3,499,171INSULATED REEL MECHANISM FOR HIGH- POWER AIRCRAFT TRAILING ANTENNARobert L. Carrel, Richard C. Fenwick, and Robert A.

Fowler, Richardson, Tex., assignors to `Collins Radio Company, CedarRapids, Iowa, a corporation of Iowa Filed May 28, 1964, Ser. No. 370,901Int. Cl. H01q l/l4 U.S. Cl. 343-877 Claims This invention relates ingeneral to a variable length airborne trailing wire antenna and inparticular to a design which provides shielding for personnel safety andprevention of undesired radiation.

At particular radio frequencies a variable length trailing wire antennaprovides the best type of antenna. The length of a trailing wire antennavaries with the frequency.

It is an object of this invention, therefore, to provide a trailing wireantenna which may be remotely adjusted in length.

Another object of this invention is to provide a trailing wire antennawhich assures personnel safety from the high voltages used in suchantenna.

Yet another object is to provide a trailing wire antenna whicheliminates capacitance in the reel supporting the unused portion of theantenna wire.

A feature of this invention is found in the provision for an enclosedcontainer which is insulated from a cover member which is electricallyconnected to the air frame so that shielding is provided by the innercontainer and which has remote control for adjusting the length of thetrailing wire antenna.

Further features and objects of the invention will become apparent fromthe following description and claims when read in view of the drawingsin which;

FIGURE l is a sectional view of the trailing wire antenna systemaccording to this invention,

FIGURE 2 is an enlarged cutaway detailed view of the apparatus formoving the electrical plug associated with the reel motor and FIGURE 3is an enlarged detailed view of the plug shown in FIGURE 2.

FIGURE 1 illustrates a transceiver 10 which is mounted in the fuselageof an aircraft and which has a coaxial cable feed line 11 containing anouter conductor 12 and an inner conductor 13 separated by insulation ina conventional manner.

An outer container 14 is formed with a base 16 which may be suitablymounted to the aircraft structure by bolts 17 and 18. The container 14is constructed of electrically conducting material and the bolts 17 and18 electrically connect it to the aircraft fuselage and aircraft skin19. This assures that the container 14 is at ground potential.

Supported within the container 14 is an inner container 21 also formedof electrical conducting material. The base 22 of the inner container 21is supported and attached to the outer conductor by insulating supports20, 23, 24, 25 and 26. These insulating supports comprise dielectricplates. Plates and 25 are longitudinal of the containers and plates 23,24 and 26 are transverse of the containers. The dielectric platesinsulate .the inner and outer containers from each other. The outerconductor 12 of the coaxial cable 11 is electrically connected to theouter container 14 and the inner container 13 is electrically connectedto the side wall 27 of the inner container 21. A drive motor 28 ismounted within the inner container 21 by a suitable supporting bracket29 and has an output shaft 31 which carries a gear 32. A belt 33 passesover gear 32 and is in mesh with a gear 34. Gear 34 is mounted on theshaft 36 of the storage reel 37 which is supported by bracket 38 fromthe base ICC of inner container 21. The reel 37 contains a supply ofantenna wire 39 which extends from the reel across a feed roller 41which is supported by suitable bearings carried by bracket 42. Bracket42 is connected to the base 22 of the inner container 21. The antennawire 39 passes over the electrical feed roller 41 and through a tube 43which extends from the wall 44 of the inner container. The tube 43 alsoextends through the wall 46 of the outer container and through theaircraft skin 19. An outer cylinder 47 extends from inner wall 46 of theouter container to the skin 19 of the aircraft. Insulating discs 48, 49and 5t) extend between the outside of tube 43 and the inside of tube 47.A biasing drag 51 is attached to the end 52 of the trailing wire antennato give a suitable aerodynamic characteristic.

Since the inner conductor 13 of the coaxial cable 11 is attached to theinner container 21 electrical energy will be fed through the bracket 42and reel 41 to the antenna wire at point A on the reel. Thus, energy maybe radiated from the wire which extends from the aircraft skin 19.

During landings and takeoff it is desirable that the trailing wireantenna be retracted and also it is desirable to adjust the length ofthe trailing wire to tune it. To accomplish this a pair of electricalleads 53 and 54 extend from the reel motor 28 to a female plug 56mounted in the end wall 44 of the inner container. A male plug 57carries two contacts for engaging the plug 56 and is connected to feedwires 58 and 59. Feed wires 58 and 59 are connected by leads 61 and 62to movable contact 63 of a reversing switch 64. Reversing switch 64 isconnected to a suitable power supply 66. Thus, when the plug 57 is inengagement with plug 56 the reel motor 28 may be energized to turn ineither direction in response to the position of Contact 63. Thus thereel motor 28 will drive the rcel 37 to extend or retract the trailingwire antenna as desired.

At all times when the plug 57 is in engagement with plug 56, thetransmitter 10 is turned olf so that an electrical short between theouter container 12 and inner conf tainer 13 does not occur through themotor power lines 58 and 59. When the trailing wire antenna has beenadjusted to the desired length the plug 57 is retracted so that itdisengages the plug 56.

This is accomplished by an electrically insulated rotatable lead screw67 which is rotatably supported between the end wall 44 and a plate 68.Plate 68 is supported by an extension cylinder 69 that is attached tothe wall 46 of the outer container.

AS best shown in FIGURE 3 a pair of electrically nsulating guide rods 69and 71 are mounted adjacent lead screw 67 between the end wall 44 andplate 68. The plug 57 carries prongs 72 and 73 for making electricalcontact and is formed with a pair of extensions 74 and 75 which areformed with openings through which rods 69 and 71 extend.

As best shown in FIGURE 2 a gear 76 is attached on the end of lead screw67 and is in mesh with gear `77 which is carried by the shaft 78 ofmotor 79. Motor 79 is connected to the cylinder 69 by suitable setscrews 81 and 82.

A pair of retractable doors 83 and 84 are supported from the end wall 46and cover the opening formed by extension 69 when the plug 67 is in theretracted position as shown in FIGURES 2 and 3. Spring hinges 86 and 87bias the doors 83 and 84 to the open position shown in FIGURE 1.However, a pair of springs 88 and 89 have first ends connected to doors83 and 84 respectively and have their seconds ends joined by wire 91.Prong 92 of plug 57 engages Wire 91 so that when the plug 57 is moved toits retracted position wire 91 and springs 88 and 89 close the doors 83and 84 as shown in 3 FIGURES 2 and 3. As best shown in FIGURE 3 a secondprong 93 extends from plug S7 on the side opposite to prong 92 andengages a wire 94 which is attached to springs that are connectedrespectively to doors 83 and 84. Door 84 has a lip 96 which engages theend portion 97 of door 83. As best shown in FIGURE 3 openings 98 and 99and 100 are formed in the doors t0 allow the guide rods 69 and 71 andthe lead screw -67 pass therethrough. As best shown in FIGURE 1 themotor 79 is fed power by a pair of leads 101 and 102 which are connectedto the movable contact 103 of reversing switch 104. The reversing switch104 is connected to power supply 66.

Assuming that the plug 57 is in a retracted position as shown in FIGURES2 and 3, the movable contact 103 may be moved to cause the motor 79 todrive the lead screw 67 such that the plug 57 moves toward the plug 56.As the plug 57 moves toward the doors 83 and 84 springs 88 and 89 willbe released and spring hinges 86 and 87 will bias the doors to the openposition. The motor 79 will continue to run until plug 57 engages plug56 to make electrical contact, then switch 104 is opened. It is to benoted that the leads 58 and 59 are flexible to allow extension of plug57. The switch 63 may then be engaged to cause the reel motor to extendor retract the antenna. When the antenna is at the desired length theswitch 63 is opened and the switch 104 is reenergized to drive the motor79 to retract the plug 57. Plug 57 disengages plug 56 to breakelectrical contact and moves within the extension 69. As it does so theprongs 92 and 93 exert tension on wires 91 and 94 connected to thesprings and close the doors 83 and 84 as shown in FIGURES 2 and 3.

- Switch 103 is opened and the transmitter may be turned on. Since thelead screw 67 and guide rods 69 and 71 are made of insulating materialthe outer and inner container remain insulated from each other.

Some advantages of this system are:

(l) Radio frequency interference-Since the transmitter current flows onthe surface of the inner enclosure, which is surrounded by the metalouter enclosure at ground potential, there is virtually no powerradiated within the aircraft which could interfere with the aircraftinstruments and equipment.

(2) Corona control.-By controlling the outside corner radii of the innerenclosure, the inside corner radii of the outer enclosure and thespacing 'between enclosures, the corona and breakdown voltages can becontrolled. If the antenna reel and associated drive equipment were notsurrounded by an inner enclosure, the sharp corners of this equipmentwould reduce the corona and breakdown voltages.

(3) Reel capacitance- Since the antenna must operate with variouslengths of wire extended, some wire is spooled on the reel at all times.If the wire was `fed at the reel, the impedance of the antenna would beaffected by the amount of Wire spooled on the reel. ln this system thecurrent does not ow through the reel, instead it flows run bothtransverse and longitudinal so they can support very large loads appliedin any direction.

Although it is seen that this invention describes a new and noveltrailing wire antenna system it is not to be so limited, as changes andmodifications may be made therein which are within the spirit and scopeof the invention as deiined by the appended claims.

We claim:

1; A variable length airborne trailing wire antenna device for mountingin an aircraft having conductive skin comprising: an electricallyconductive outer enclosure having an opening therein; an opening formedin the conductive skin of the aircraft in alignment with the opening inthe outer enclosure, a hollow conductive-cylinder connecting the skin ofthe aircraft to the outer enclosure with the openings in the skin andouter enclosure aligned with the center opening of the hollow cylinder,an electrically conductive inner enclosure within and insulated fromsaid outer enclosure and the conductive skin of the aircraft, said innerenclosure having an opening therein in substantial alignment with theopenings in said outer enclosure and conductive skin, radio frequencymeans connected to said inner and outer enclosures, an electrical feedmeans within and connected to said inner enclosure adjacent the openingin the inner enclosure, said feed means also serving as a guide meansfor said antenna, a length of electrically conductive antenna wire, aportion of which is within said inner enclosure and engages said feedmeans and another portion of which extends through around the reel andinto the wire just before it exits the aircraft. Thus reel capacitancedoes not influence antenna impedance.

(4) Shmilt capacitance controls-By controlling the spacing between theinner and outer enclosures the shunt capacitance of the antenna may becontrolled.

(5) Lighting protection-This design facilitates the use of a lightningarrestor or spark gap between the two enclosures.

(6) Personnel safety.-Since the outer enclosure is at ground potentialpersonnel are shielded from all of the high voltage areas.

(7) Packaging-Since the reel and its drive mechanism are located withinthe inner enclosure; compact, weatherproof packaging is achieved.

(8) Structural design-The dielectric plates used to space the innerenclosure away from the outer enclosure said openings and is outsidesaid enclosures and the aircraft, and means for controlling the lengthof the portion of said antenna wire extending outside said enclosures.

2. The trailing wire antenna device of claim 1 wherein said openings insaid enclosures are small in diameter relative to the size of saidenclosures but are larger in diameter than said antenna wire so thatsaid antenna Wire freely passes therethrough.

3. The trailing wire antenna device of claim 1 wherein said meansadapting said enclosure for connection to radio signal generating andreceiving means includes a length of coaxial cable the outer conductorof which is connected to said outer enclosure and the inner conductor ofwhich is connected to said inner enclosure.

4. The trailing wire antenna device of claim 1 wherein said guide meansincludes a metallic roller adjacent to said opening in said innerenclosure.

i. The trailing wire antenna device of claim 1 wherein said antenna wirewithin said inner enclosure is stored on a reel and engages said guidemeans only after being unwound from said reel.

6. The trailing Vwire antenna device of claim 5 wherein said last namedmeans includes an externally controlled motor, said motor beingconnected to said reel to adjust the length of said antenna wire outsidesaid enclosures.

7. A variable length airborne trailing wire antenna for an aircrafthaving conductive skin comprising: an electrically conductive outerenclosure electrically connected to the skin of the aircraft and havinga small insulated 4opening therein, an opening in the aircraft skin, ahollow conductive cylinder connected between the aircraft skin and theouter enclosure with the central opening of the cylinder aligned withthe openings in the'skin and outer enclosure, an electrically conductiveinner enclosure within and insulated from said outer conductor, saidinner conductor having a small opening therein in substantial alignmentwith the openings in said outer enclosure and the skin, a coaxial cablethe inner conductor of which is connected to said inner enclosure andthe outer conductor of which is connected-t0 said outer enclosure, aradiant energy device connected to the other end of said coaxial cable;electrically conductive feed and guide means mounted within said innerenclosure adjacent to said opening therein; a reel rotatably mountedwithin said inner enclosure; antenna wire a portion of which is wound onsaid reel and another portion of which engages said feed and guide meansand extends from said enclosures and the aircraft through said openingstherein; a motor connected to rotate said reel; and control meansconnected to said motor to control the amount of antenna wire extendingfrom said enclosures and the aircraft.

8. The trailing wire antenna device of claim 7 wherein said outerenclosure has a second opening therein; wherein said control meansincludes plug means one portion of which is mounted on said firstenclosure and the other portion of which is retractable from saidenclosure through said second opening in said outer enclosure; andfurther characterized by means for automatically closing said secondopening upon retraction of said other portion of said plug means.

9. The trailing wire antenna device of claim 8 wherein said last namedmeans includes doors actuated by said other portion of said plug meansduring retraction.

References Cited UNITED STATES PATENTS 2,036,456 4/1936 Buschbeck343-877 XR 2,374,892 5/1945 Peterson 343-877 XR 2,834,012 5/1958 Allen.343-877 XR RODNEY D. BENNETT, J R., Primary Examiner J. P. MORRIS,Assistant Examiner U.S. Cl. X.R. 343--723

1. A VARIABLE LENGTH AIRBORNE TRAILING WIRE ANTENNA DEVICE FOR MOUNTINGIN AN AIRCRAFT HAVING CONDUCTIVE SKIN COMPRISING: AN ELECTRICALLYCONDUCTIVE OUTER ENCLOSURE HAVING AN OPENING THEREIN; AN OPENING FORMEDIN THE CONDUCTIVE SKIN OF THE AIRCRAFT IN ALIGNMENT WITH THE OPENING INTHE OUTER ENCLOSURE, A HOLLOW CONDUCTIVE CYLINDER CONNECTING THE SKIN OFTHE AIRCRAFT TO THE OUTER ENCLOSURE WITH THE OPENINGS IN THE SKIN ANDOUTER ENCLOSURE ALIGNED WITH THE CENTER OPENING OF THE HOLLOW CYLINDER,AN ELECRICALLY CONDUCTIVE INNER ENCLOSURE WITHIN AND INSULATED FROM SAIDOUTER ENCLOSURE AND THE CONDUCTIVE SKIN OF THE AIRCRAFT, SAID INNERENCLOSURE HAVING AN OPENING THEREIN IN SUBSTANTIAL ALIGNMENT WITH THEOPENINGS IN SAID OUTER ENCLOSURE AND CONDUCTIVE SKIN, RADIO FREQUENCYMEANS CON-